This invention relates generally to densitometers and, more particularly, to an improved diagnostic densitometer which provides both analog and digital outputs and which interprets the outputs to provide a preliminary medical diagnosis.
Densitometers are well-known as devices which scan a sample and provide an output signal or graphical display indicative of the optical density, transmittance, absorption or the like of the scanned sample.
One well-known use of the densitometer is to scan a sample of blood which has been prepared by the electrophoresis process. Electrophoresis of blood samples isolates various proteins in the blood, known as albumin, alpha-1 globulin, alpha-2 globulin, beta-globulin and gamma-globulin. The electrophoresis technique separates these proteins from each other and then the sample may be processed or scanned in a densitometer. Each of the proteins exhibits a different light absorption characteristic or pattern and the light absorption patterns are graphically displayed by the densitometer to indicate the presence and quantity of each of these proteins.
The graphical display may include a first analog signal or curve which exhibits a series of peaks and valleys. In the analysis of blood, the area under the optical density curve and bounded by the two adjacent valleys separated by one peak, is representative of the quantity of each protein in the sample and is referred to a sample fraction. The important data is the relative percentage of each protein and the selection of these fraction boundaries, i.e., the precise locations of these valleys is somewhat arbitrary and results in inaccurate analysis of the blood sample. The problem is not unique to evaluation of blood samples, but is common to optical and magnetic density valuations and, in fact, to all evaluations of analog data.
It is known, according to the prior art, to provide a microprocessor-controlled densitometer to scan an electrophoretically prepared sample and provide both an analog signal or curve of the optical density and digital (i.e., numerical) data representative of the quantity of each protein and/or the relative amount of each protein in the sample. Such a densitometer is described, for example, in U.S. Pat. No. 4,242,730 of Golias et al issued Dec. 30, 1980.
Heretofore, once the analog and digital data were provided by the densitometer a physician would interpret the data and provide a medical diagnosis. The diagnosis, of course, would be based upon the physician's own prior experience, education and knowledge, and would also be based upon other medical information about the patient.
Prior to the present invention it was also known that computers could be provided with a data base and could make decisions based upon a comparison of self-generated or externally provided data with the data base.
For example and not by way of limitation, Japanese Pat. No. 28834 of Apr. 3, 1977 discloses a device which attempts to identify a disease based upon data contained in a data base plus the input of clinical data with respect to an individual patient.
Jones et al U.S. Pat. No. 3,977,394 of 1976 relates to a computerized pulmonary analyzer and, more specifically to a programmable digital computer which receives a signal representative of the volume of air expelled by a patient upon exhaling, and with the computer comparing the test results with internal standardized values and providing an output signal comparing the test data to the standardized values.
U.S. Pat. No. 4,199,748 to Bacus relates to a method and apparatus which assists in diagnosis for anemic blood and the like by comparing microscopic slides to a pattern recognition program.
U.S. Pat. No. 4,186,748 to Schlager describes a thermographic analytical apparatus for determining the presence of cancer and includes a pattern recognition program to provide an automated diagnosis of particular medical conditions.
None of this prior art, however, taken alone or in combination recognizes the problem that the computer-generated data, i.e., the computer's analysis of the sample prior to comparison with the data base, may be incorrect.
The preliminary work leading up to the present invention was published July 1981 in the Medical Laboratory Observer published by the Medical Economics Company of Oradell, N.J. 07649, entitled "Computerized Diagnosis in the Lab". The aforementioned article relates, in general, to the internal decision making process for programming a computer. The article explains that a scanning densitometer equipped with an interpretive program for serum protein electrophoresis is already undergoing testing and evaluation at the clinical laboratory of Overlook Hospital in Summit, N.J.
Of course, as the article correctly points out, once a working computer program model has been created, computer interpretations and computer diagnoses must be compared with the physician's independent diagnoses to confirm the accuracy of the computer model and, of course, the computer model must be repeatedly refined until the computer interpretation results in acceptable percentage of agreement with the physician's own diagnosis. At that point in time, according to standardized techniques, the computer program can be burned into a ROM and provided as a part of the densitometer.
To further understand the present invention, it should be understood that according to the aforementioned Golias et al patent, when a blood sample or the like which has been electrophoretically prepared is optically scanned, an analog signal is provided which is a function of the optical density of the scanned sample. The analog signal has a plurality of peaks and valleys and the integral of the analog signal, commonly referred to as the area under the curve, is representative of the total serum protein present in the sample. According to the prior art Golias et al patent, a microprocessor-controlled densitometer has the ability to select the valleys within the analog signal and separately compute the area under the curve between adjacent valleys thus providing the serum protein fractions referred to as albumin, alpha-1, alpha-2, beta and gamma. These individual fractions are quantified according to the prior art and the numerical values, percentages, and analog output are all utilized by the physician to assist in the diagnosis of the condition of the patient from whom the blood sample was obtained.
As previously indicated, the computer's determination of the location of the valleys (i.e., computer self-generated data) may not be correct. The physician has the analog curve available for use in diagnosis, which is critical if the physician disagrees with the computer's selection of the "valleys". But the prior art does not suggest the use of external data, including confirmation or modification of the computer-selected data (e.g., valleys).
Thus prior to the present invention the physician must accept the computer generated data in order to accept the "diagnosis" i.e., the comparison to the data base.